This invention relates to a door closing device for urging an opened door towards its closed position relative to a doorframe.
More particularly, the invention concerns improvements in a door closer, which is of the kind that usually acts between a door leaf and a doorframe. This type of door closer typically comprises a housing, a plunger movable along the housing, a biasing element disposed in the housing and biasing the plunger inwardly of the housing, and a tension member having one end connected to the plunger and another end, which extends to an anchor element. The housing is normally installed in a bore in the door leaf and the anchor element installed in the doorframe. However, the positions of the housing and the anchor element may be reversed. The biasing element comprises a spring, which operates to bias the plunger, and consequently the tension member, inwardly of the housing, for closing the door. The tension member comprises an articulated element so that the tension member can be bent around the opening angle of the door relative to the door frame.
It is known to provide such concealed door closers with a hydraulic damping assembly, as disclosed for example in GB-A-2441893, GB-A-2441894, WO-A-2005/124079 and WO-A-2008/102115. The hydraulic damping assembly comprises a piston and cylinder assembly that can damp the movement of the plunger. The hydraulic damping assembly comprises circuit for the hydraulic fluid that incorporates an adjustable valve assembly. The valve can be adjusted to vary the damping force of the hydraulic damping assembly.
Recently, a standard classifying controlled door closing devices has been established as BS EN 1154 1997, with Amendment A1 2003. Door closers intended for use on fire resisting doors and smoke control doors are covered by a Construction Products Directive mandate issued by the European Commission, and the Amendment A1 to the BS EN 1154 1997 harmonised the standard in compliance with the Directive and allows application of the CE mark. The standard sets minimum performance parameters for door closer operation, in particular with regard to closing moment (dependent on door size and mass) and closing time.
While face fixed overhead closers can readily be constructed so as to comply with BS EN 1154 1997, because a bulky housing can be provided which merely needs to fit to the door face or the frame, in contrast concealed door closers of the type disclosed in EP-A-0016445 generally cannot, primarily as a result of the inherently low power characteristics of this construction, because the spring needs to be dimensioned to fit within the door leaf without compromising the structural integrity of the door, which is crucial for fire resisting doors, for example.
There is a need in the art for concealed door closers that can comply with BS EN 1154 1997.
There is also a general need for such concealed door closers to have a structure to enable them to be incorporated into a variety of different door constructions having a variety of different uses. For example, the British Standard BS.EN 1154, and its equivalent European Standard EN 1154, sets (among others) a technical criterion required to be met by door closers, concealed or not, which is that the door closer must have a minimum opening/closing efficiency—the closer must provide a minimum resistance force in an opening direction, to enable a person readily to be able to pull open the door, but must provide a maximum closing force, to enable the door reliably to be closed under the action of the door closer, overcoming any resistance from the door latch, in order to ensure that the door closer can properly and promptly act to close the door, which provides safety in the event of a fire.
We have found that for concealed door closers incorporating a hydraulic damping assembly this demanding performance criterion is difficult to meet because the door closer can suffer from inadvertent jamming, and because it is necessary to ensure that the door closes completely, which means a reliable high closing force right at the end of the closing stroke to overcame any resistance to closing from the latch mechanism for the door.
Even for non-concealed “up and over” door closers, the efficiency can be quite low, for example 60 to 70%.
In addition, the fitting of concealed door closers even by professional workers such as builders, joiners, etc. can be rather problematic. The door closer incorporates a mechanical spring having a high spring constant, which applies a very high tensile restoring force to pull together the two parts of the door closer which are fitted to the door frame and to the door leaf. These parts need to be separate during installation. Furthermore, sometimes the door closer maybe inadvertently fitted incorrectly, for example “inside out” with the tensioning member between the two parts having the edge that should be oriented on the radially inside side of the closing arc being located o the radially outside edge. Although a fitting tool is disclosed in WO-A-2008/102115 to assist installation, there is still a need for an “idiot proof” fitting tool to ensure that the door closer is correctly fitted in the required orientation.